After being shot into its orbit, a satellite of the above-indicated type must be aligned with respect to earth and sun, particularly to optimize the antenna gain and the illumination of the solar cells.
In the known Symphony satellite (Symphonie-Satellit), see also the magazine Flugrevue 1/1975, pages 39-40, for the alignment of the satellite after reaching a quasi-synchronized orbit, the spin rate is reduced from about 120 rotations/minute to about 2 rotations/minute and the solar cell paddles are folded out. After a momentum wheel has been accelerated to normal speed, the spin rate is measured by means of solar sensors and, if necessary, is corrected by means of a cold-gas system. By means of another cold-gas pulse, the spin rate is further reduced and the z-axis is aligned relative to the earth while measuring or surveying with infrared sensors. The satellite is subsequently rotated about the z-axis until the x-axis is perpendicular relative to the plane of the trajectory. An additional fine sensor is used for the fine alignment of the satellite. To avoid the incidence of reflected light, the sensors are screened by means of light shields.
It is of significant importance for various reasons that the satellite concludes the acquisition maneuver as quickly as possible. The heat balance with respect to overheating as well as under-cooling does not allow the exposure of sensitive parts of the sun longer than intended, or to leave them in the shadow, otherwise an increase in the operational risk occurs. Also, it must be possible to use the solar cells as quickly as possible to meet the energy requirements, however, they should not cover the sensor heads. Accordingly, quick unfolding and alignment toward the sun are desired.